Return to The Green Energy Institute Home Page

Wednesday, March 16, 2016

Daylight Savings Time: Who Stole my Hour and Why?

By Andrea Lang, Energy Fellow

Last
Sunday, Americans (save Hawaiians and most Arizonans) lost an hour of their
weekend to daylight saving time. While many Americans have a vague
understanding that daylight savings time is meant to save energy, others mistakenly
believe that the policy was designed to help farmers (in fact, most farmers have been opposed to daylight savings time from the
beginning). Today’s blog dives into the history and justification for daylight
savings time, and examines the studies into its efficacy in terms of energy
conservation.

I say it is impossible
that so sensible a people…

should have lived so long by the smoky, unwholesome,

and enormously expensive light of candles,

if they had really known, that they
might

have had as much pure light of the sun for nothing.

–Benjamin
Franklin

Who thought daylight
saving time up?

Many attribute the idea of daylight savings time to Benjamin
Franklin’s 1784 essay in the Journal of Paris. Mr.
Franklin wrote in that essay about the expense of candles used in the dark hours of the evening
and the wasted daylight hours spent sleeping in the morning. He jokingly
suggested that “[e]very morning, as soon as the sun rises, let all the bells in
every church be set ringing; and if that is not sufficient?, let cannon be
fired in every street, to wake the sluggards effectually, and make them open
their eyes to see their true interest.”

We can all be thankful that Benjamin Franklin’s solution of
firing off cannons at sunrise every morning was never adopted. Instead, a New
Zealand entomologist seeking more daylight hours by which to examine insects first proposed the idea of adjusting the time, resulting in the first daylight
savings time in 1917 New Zealand. Until the US permanently adopted a daylight savings time in the mid 1960s, it was purely a
wartime policy. During World War I, Congress passed the
first daylight savings law in 1918, but repealed it just a year later in
1919. Another daylight savings time law during World War II lasted from
1942-1945. It wasn’t until 1966 that Congress established a permanent daylight
savings schedule for the purpose of conserving energy. That schedule has been
periodically changed to shift or expand daylight savings time. The existing
schedule was established by the Energy Policy Act of 2005, which extended
daylight savings time by several weeks.

Does it make sense?

I was able to find two recent American studies on the electricity
savings afforded by daylight savings time, both conducted in 2008. Each comes
to a conflicting conclusion:

The first study is a Department of Energy (DOE) report to
Congress that was required by the Energy Policy Act of 2005. The DOE study simply compared annual electricity consumption between different
years, using the difference between the electricity used in the added weeks of
daylight savings and the electricity used before the 2005 act extended daylight
savings. It concluded that the total electricity savings amounted to 1.3
Terawatt-hours, amounting 0.5% per day in electricity savings.

On the other hand, a different independent 2008 study found
that daylight savings time actually increases electricity demand by 1%, at
least in Indiana. That study used data from Indiana, where various counties had historically
practicing daylight savings time, while others had not. When a 2006 state law
required all counties to begin practicing daylight savings time, the
researchers took advantage of the unique circumstances that created a set of
treatment and control data sets. The ability to use a control set of data makes
this study more appealing than the DOE study, because it allowed the
researchers to say more definitively whether energy savings or losses were a
result of the policy itself. The study concluded that although Benjamin
Franklin was correct that daylight savings time saves on electricity used for
lighting, those savings are more than offset by an increase in consumption used
for heating and cooling.

Credit:NIH.gov

Both
studies have their limitations. As I’ve noted, the DOE study is simplistic and
lacks a control data set to confirm the cause of the alleged 0.5%/day savings.
The Indiana study, while well designed, is specific to Indiana, which
experiences more seasonal variation than many other states. More temperate states
may use less energy for heating and cooling. Regardless, given the conflicting
results of the two 2008 studies, it’s surprising to me that more haven’t been
conducted.

Perhaps I’m just grumpy about my lost hour of sleep on
Sunday, but the justification for daylight savings time seems dubious at best.
While energy conservation is an important goal, it may be past time to
reevaluate whether daylight savings is the best policy to that end.